1. Field of the Invention
The invention relates to a high-efficiency high step-up ratio direct current converter with an interleaved soft-switching mechanism.
2. Description of the Related Art
It can be said that modern high technology civilization is developed on a base of massive consumption of petrochemical energies. According to the researches and statistics, however, the petrochemical energy will be gradually consumed, and the storage amount of global petroleum fuel could afford us for use less than forty years. When the petrochemical energy is utilized to improve quality of life, a large amount of greenhouse gases are simultaneously produced, resulting in greenhouse effect and damages of nature ecological environment. In view of increasing price of petroleum every day, many countries in the world begin to promote energy saving and carbon reduction. Also, clean renewable energies such as solar energy, wind power and fuel cell are gradually valued, and thus energy technologies connected therewith are gradually applied and developed.
It is difficult to build a large renewable energy generation system on an island with small area but densely populated due to space limitation, and therefore a small distributed electric power system is gradually valued. A small renewable energy can be composed of electric power conversion circuits such as a solar photovoltaic module or fuel cell, a step-up DC/DC converter, a DC/AC converter, etc. In general, a solar or fuel cell supplies a low voltage DC power (20V-45V). However, a post-stage DC/AC converter requires a higher DC input voltage (350V-400V) for conversion into a commonly-used AC (110 Vrms, 220 Vrms), thereby supplying to a load or parallel operation with the utility. Therefore, it is essential to use a high step-up ratio DC/DC converter to attain a front-stage step-up purpose. However, due to a large current input of such a high step-up ratio DC/DC converter, larger current ripple and flip-flop switching loss are easily occurred therewith.